Minimum And Maximum Power Per Output; Attenuators; Examples Of Irregularities That Cannot Be Recognized; Connecting Priority Relays - Monacor MEVAC-4 Bedienungsanleitung

4.2.3 Minimum and maximum power per output

To obtain reliable measuring results, a minimum load of
P > 10 W per path must be installed for each output (i. e.
min
a total load of at least 20 W for each zone output). The im-
pedance of the speaker line must be less than 1 kΩ at 22 kHz.
For each zone output (path A and path B combined),
the maximum power connected must not exceed 500 W!

4.2.4 Attenuators

Attenuators are often used in a 100 V speaker line to con-
trol the volume in specific sections. Modern attenuators are
equipped with a priority relay which can be controlled exter-
nally to make sure that evacuation announcements can be
transmitted even when the attenuator is switched off (see
chapter 4.2.6).
Using attenuators in monitored speaker lines is always
problematical because, during operation, the attenuator may
substantially change the impedance of a speaker line. The
attenuator has a control range of 0 – 100 % of the speaker
power; therefore, MEVAC-4 may not always recognize the
speakers connected.
MEVAC-4 ATT-5..PEU
IN
GND 1
+24 V
GND
Fig. 8 Attenuator of the series ATT-5...PEU with priority relay
Example: The controller is in its maximum position during the
installation run and is then set to 50 % during operation; this
may be recognized as a deviation of more than 20 W and a
corresponding error message will appear. If the attenuator
is in operation during the installation run, the speaker line
connected may not be recognized as installed.
Therefore, always observe the following:
When using attenuators, always switch off impedance
monitoring of the corresponding speaker lines in order to
avoid unwanted error messages (chapter 7.4).
In addition, terminate the speaker line with a 1 kΩ resistor
(10 W min.); otherwise, the error message "Open Line" will
appear.
4.2.5 Examples of irregularities
that cannot be recognized
Example
Line A
1 P = 10 W
2 P = 36 W
30
Speaker 1
10
OUT
Volume
0
GND 1
Line B During the installation run
the load at line B is not
P = 6 W
recognized
P = 18 W,
the load at line B (9 W) may
attenuator
not be recognized
at 50 %

4.2.6 Connecting priority relays

Emergency power supply
permanent
24 V output
observe max. power
rating!
GND +24 V
Fig. 9 Priority relay
Attention: The load of the relay "PRI REL" installed in the
MEVAC-4 system must not exceed 2 A. If more
than 2 A are required for controlling the priority
relay and /or if an external power supply unit is to
be used, the connection must be as follows:
Emergency power supply
permanent
24 V output
observe max. power
rating!
GND +24 V
Speaker ...
Fig. 10 External power supply for priority relay
The unswitched (permanent) outputs of the emergency power
supply can be used as the 24 V DC power supply for the pri-
ority relays.
At the emergency power supply PA-
24ESP, connect the 4-pole Phoenix ter-
minal shown to the right (+24 V to PIN 3,
negative / GND to PIN 1). The maximum
load of this connection is 1 A. MEVAC-4
requires approx. 600 mA (also see chapter
5.6) so that approx. 400 mA are availa-
ble for the priority relays connected. If
more power is required, use a separate
power supply unit for the priority relays
(see fig. 10).
When the emergency power supply EVA-
24 /54 is used, connect one of the out-
puts 7, 8 or 9 (each 3 A max.). Do not
use the output that is used as the emer-
gency power connection for MEVAC-4
(see chapter 5.6)!
MEVAC-4
POW PRI SYS
Attenuator
FAIL REL ERR
24 V switching input
for the
priority relay
CON CON CON
+24 V
MEVAC-4
POW PRI SYS
Attenuator
FAIL REL ERR
24 V switching input
for the
priority relay
CON CON CON
+24 V
+ 24 V −
+24 V
4
Fig. 11
Permanent 24 V out-
put of PA-24ESP
7 8
Fig. 12 24 V outputs
of EVA-24 / 54
GND
GND
GND
1
9